Set screw electrical connectors are commonly used to connect or splice distribution cabling to a bus bar. Such connectors generally include a rectangular aluminum or conductive alloy body having a series of openings therein sized to accommodate a transformer stud, prepared cabling and the associated set screws securing the stripped conductors or the cables to the connector. These connectors are often found in locations that are exposed to moisture or are underground. Thus, the connector should provide for water tight connection.
U.S. Pat. No. 5,533,912 discloses a typical design for a set screw electrical connector that prevents water from entering therein. This design encapsulates the connector body with somewhat flexible water-impervious material. The encapsulation includes a series of hollow sleeves which project from the connector body. Certain of the sleeves are designed to accept the cabling therein while others are sized to accommodate the metal set screw. Once the set screw is tightened against the stripped wire conductor, a removable plug or cap is then inserted into this sleeve to seal the opening. A drawback of this typical design is the likelihood that one or more plugs will be lost or not inserted and thus the entire connector will be compromised. Another drawback is that when the user tightens the set screw, there is the risk of electrical shock hazard because the tool employed by the user is usually metal and such a tool will readily conduct electricity directly to the user or to any object coming into contact with the tool during installation if the cable is energized.
U.S. Pat. No. 6,764,354 discloses a variation of the above in that it incorporates a wholly plastic set screw having a threaded lower body portion, a round intermediate body portion and a hex head. The lower body portion is threaded into the connector to secure the cabling in place while the round intermediate body portion forms a seal with the encapsulating material. Obviously, one drawback to this design is the great difference in strength between the metal threads of the connector and the plastic threads of the set screw. Stripping of the plastic threads is likely and thus inadequate compression of the bare conductor will result. This can cause arcing within the connector that will lead to failure. Also, by eliminating the metal set screw, there is less electrical contact between the bare conductor and the electrical connector.